Power Semiconductor Device Having Layered Structure of Power Semiconductor Elements and Terminal Members
1. Field of the Invention
The present invention relates to a power semiconductor device, and more particularly to a technique to eliminate wire connection and solve problems caused by the wire connection.
2. Description of the Background Art
There is a need, recently, for a downsized and lightweight, low-cost and high-quality power semiconductor device. Though high quality generally costs a lot, it is desired to ensure high quality with cost reduction.
FIGS. 26 and 27 are schematic plan view and cross section illustrating a power semiconductor device 51P in the background art. Herein, as an example of the background-art power semiconductor device 51P, one-phase structure (one arm) of a three-phase inverter is taken. For simple illustration, a case body (resin member) is omitted in FIGS. 26 and 27.
In the background-art power semiconductor device 51P, metal layers 152P and 153P made of, e.g., copper or aluminum are disposed on both main surfaces of a radiating insulating substrate 151P made of, e.g., ceramic. The insulating substrate 151P is adhered onto a metal radiator plate (not shown) made of, e.g., copper or aluminum with solder.
On each metal layer 152P, IGBTs 121P and 122P and free wheeling diodes 131P and 132P are disposed (four power semiconductor elements 121P, 122P, 131P and 132P are disposed on a plane), being in an electric contact with the metal layer 152P. Wires 154P made of aluminum or gold establish connection between a pair of power semiconductor elements 121P and 131P and between another pair of power semiconductor elements 122P and 132P. Further, the power semiconductor elements 121P, 122P, 131P and 132P are connected to the metal layer 152P and terminals 155P and 155PP with the wires 154P. The metal layer 152P and a terminal 155NP are connected to each other with the wires 154P. The terminals 155NP and 155PP are connected to low potential (power-supply ground potential) and high potential, respectively.
A case (now shown) is so arranged as to house the power semiconductor elements 121P, 122P, 131P and 132P and filled with epoxy resin. At this time, in some cases, the power semiconductor elements 121P, 122P, 131P and 132P are sealed by silicone gel and the epoxy resin fills thereon.
The background-art power semiconductor device 51P has the following problems caused by the wires 154P.
First, disconnection is disadvantageously caused by a break of the wire 154P. For example, when the power semiconductor device 51P is used in automobile, motorbike, train or the like, vibrations sometimes cause a crack in a neck portion of a wire, resulting in disconnection.
Further, the need for providing connecting portions of the wires 154P causes upsizing of the power semiconductor device 51P.
Furthermore, a voltage drop of the wire 154P causes a power loss.
It is a main object of the present invention to provide a power semiconductor device having no wire connection.
According to the present invention, a power semiconductor device includes first to third terminal members, at least one first power semiconductor element, and at least one second power semiconductor element. The first to third terminal members each include an element arrangement portion having first and second main surfaces which are opposed to each other. The at least one first power semiconductor element has first and second main surfaces which are opposed to each other and first and second main electrodes provided on the first and second main surfaces, respectively. The at least one second power semiconductor element has first and second main surfaces which are opposed to each other and first and second main electrodes provided on the first and second main surfaces, respectively. The at least one first power semiconductor element has the same structure as the at least one second power semiconductor element. The second main surface in the element arrangement portion of the first terminal member is joined to the first main electrode of the at least one first power semiconductor element. The second main electrode of the at least one first power semiconductor element is joined to the first main surface in the element arrangement portion of the second terminal member. The second main surface in the element arrangement portion of the second terminal member is joined to the first main electrode of the at least one second power semiconductor element. The second main electrode of the at least one second power semiconductor element is joined to the first main surface in the element arrangement portion of the third terminal member. The power semiconductor device further includes a package for housing the at least one first power semiconductor element and the at least one second power semiconductor element. The first to third terminal members each have an external connection portion drawn out of the package.
Since the terminal members and the power semiconductor elements are alternately layered, being joined to one another, and the external connection portions of the terminal members are drawn out of the package, it is possible to provide a power semiconductor device having no wire connection. Therefore, according to the power semiconductor device of the present invention, it is possible to solve the problems caused by the wire connection. Further, while a manufacturing time becomes longer as the number of wires (depending on the current rating) increases, the power semiconductor device of the present invention has a structure in which the terminal members and the power semiconductor elements are joined to one another regardless of the current rating and thereby shows outstanding productivity. Furthermore, such a structure as discussed above in which the terminal members and the power semiconductor elements are alternately layered ensures downsizing. Moreover, since the first power semiconductor element and the second power semiconductor element have the same structure and there is no need for preparing any power semiconductor element of different structure, it is possible to reduce the cost.